Various fluids, such as whole blood or various other biological fluids may be separated into their constituent parts, also referred to as fractions or phases. For example, whole blood samples may include a plurality of constituents that may be separated by density in a device such as a centrifuge. The whole blood sample may be placed in a test tube, or other similar device, which is then spun in a centrifuge. In the centrifuge the whole blood is separated into different fractions depending upon the density of that fraction. In addition, various elements may be added to the test tube to create more than two fractions. In particular, commonly used gels may be used to divide the whole blood into a plurality of different fractions which may include fractions such as buffy coat platelets, red blood cells, and plasma. Various other biological fluids may be separated as well. For example, nucleated cells may be separated and extracted from bone marrow or adipose tissue sample.